Question about length and volume

I am having a board shaped for more hollow waves(thruster-short board), and the shaper recommends going a couple inches longer than my current board , but keeping about the same amount of volume, just stretching it out with changes with the rocker ect… How does the length help if the volume is the same? I trust my shaper, I’m just curious about the function of length. Can anyone help out? Thanks

When your board is being paddled, it’s a displacement hull and how it floats and paddles is mostly governed by it’s displacement: the volume of it.

When it’s in use on a wave, the planing area comes into play and the volume becomes irrelevant. It’s planing, you see, not floating. Otherwise, for instance, water skis would have to be six inches thick in order to float the guy using 'em.

Also aspect ratios and such may play their parts which is perhaps why he’s suggesting same width and such stretched out over the slightly greater length .

hope that’s of use

doc…

Your shaper is on the right track, what he’s trying to do is give you a board that

will “feel” the same as your everyday board. If you’re in bigger, hollower surf the

“step-up” type board is designed to do all the things your everyday board does,

just in better surf. A little bit longer board loosens right up in more powerful waves.

Keeping the volume the same maintains that “feel”. The added length takes out

twitchiness and gives you a bit longer rail to carve on. If you want to get in the

wave easier/earlier, go up a little on volume.

Mike

Thanks Mike and Doc! Very enlightening.